1. Field of the Invention
The present invention relates to a substrate storage pod in which substrates such as semiconductor wafers are stored in a hollow inner space to be conveyed, and more particularly, to a front opening unified pod (FOUP) which performs opening and closing of a lid on a front side, and has a replacement function with respect to a clean gas in the hollow inner space. The present invention also relates to a processing apparatus for substrates such as semiconductor wafers, the processing apparatus meeting a front-opening interface mechanical standard (FIMS) for the FOUP.
2. Description of the Related Art
Processing operation on substrates such as semiconductor wafers (hereinafter, referred to as “substrates”) includes multiple processing steps. Those processing steps are performed in a clean room which has a certain size and secured cleanliness. In the clean room, there are arranged processing apparatuses for performing respective processing steps. An interior space of each of the processing apparatuses has cleanliness maintained to be higher than that in the clean room in which the processing apparatuses themselves are arranged. The substrates undergo processing in the interior space of each of the processing apparatuses. When being moved from apparatus to apparatus, the substrates are conveyed while being housed in a FOUP housing pod (hereinafter, referred to as “pod”). High cleanliness and an oxidization-resistant environment are maintained in the pod, and hence it is unnecessary to control the environment of the entire of the wide clean room. As a result, control and management can be efficiently performed; specifically, only ambient atmosphere around the substrates (minute volume relative to a volume of the clean room) has to be maintained in the high-cleanliness and oxidization-resistant states.
FIG. 4 illustrates a conventional pod 1 in a state of being placed on a processing apparatus 20. Generally, the pod 1 includes a lid member 2 and a pod case 3. The pod case 3 has an opening 3a formed at one end thereof. The lid member 2 is capable of sealing the pod case 3 by closing the opening 3a. The pod case 3 includes a shelf 5 arranged therein. The shelf 5 includes multiple stages arranged in pairs in parallel with each other in a vertical direction. Each pair of the multiple stages is generally arranged horizontally, and is capable of holding corresponding one of substrates.
An interior space 20a of the processing apparatus 20 is used in processing steps performed on the substrates. The interior space 20a of the processing apparatus 20 has cleanliness maintained to be higher than ambient atmosphere in a clean room. In the interior space 20a of the processing apparatus 20, there are arranged a transfer robot, a processing device, and the like. The processing apparatus 20 has a wall portion provided with an access opening 20b for access from an outside of the processing apparatus 20 into the interior space 20a of the processing apparatus 20. When the access from the outside of the processing apparatus 20 into the interior space 20a is not performed, as illustrated in FIG. 4, the access opening 20b is closed by a FIMS door 21 (hereinafter, referred to as “door”). The processing apparatus 20 includes a load port portion 22 for placing the pod 1 thereon. The load port portion 22 functions to place the pod 1 so that the pod 1 faces the access opening 20b. That is, first, when processing steps are performed on the substrates, the pod 1 is placed on the load port portion 22 of the processing apparatus 20. On the load port portion 22 of the processing apparatus 20, the pod 1 is properly placed so that the opening 3a of the pod case 3 of the pod 1 faces the access opening 20b of the processing apparatus 20. After that, the load port portion 22 performs predetermined positioning operation on the pod 1. Simultaneously with opening and closing of the access opening 20b of the processing apparatus 20, the opening 3a of the pod case 3 of the pod 1 is opened. For example, generally, the door 21 holds the lid member 2 of the pod 1 so as to simultaneously open the access opening 20b of the processing apparatus 20 and the opening 3a of the pod case 3 of the pod 1. In this state, the substrates respectively placed on the pairs of the stages are moved in a horizontal direction so as to be taken out from the inside of the pod 1 through the opening 3a. Then, the substrates are transferred into the interior space 20a of the processing apparatus 20, and undergo the processing steps. Further, after completion of the processing steps, the substrates are transferred from the interior space 20a of the processing apparatus 20 into the pod 1 through the opening 3a. In this manner, the substrates are returned to predetermined pairs of stages of the shelf 5 in the pod case 3 in the pod 1.
When all the processing steps on the substrates in the pod 1 are completed, the door 21 of the processing apparatus 20 re-closes the access opening 20b of the processing apparatus 20. With this, the opening 3a of the pod case 3 is sealed by being closed by the lid member 2 of the pod 1, the lid member 2 being held by the door 21. In this stage, atmosphere in the pod case 3 is ambient atmosphere in the interior space 20a, the ambient atmosphere containing dust and oxygen. In order to maintain the substrates to be clean until the subsequent steps, it is necessary to remove the dust in the atmosphere so that gas components liable to react with surfaces of the substrates are removed. Therefore, generally, after the lid member 2 closes and seals the pod case 3, the atmosphere in the pod 1 is replaced with an inert gas (hereinafter, referred to as “replacement gas”).
Conventional examples of means for replacing the atmosphere in the pod 1 with an inert gas include various ones. For example, Japanese Patent Application Laid-Open No. 2003-17553 and Japanese Patent Application Laid-Open No. 2003-60007 each discloses a pod of such a type that the air is supplied and exhausted through a bottom surface. In the pods of this type, as illustrated in FIG. 4, an air-supply port 12 and an exhaust port 13 are arranged in a lower portion of the pod case 3 of the pod 1. When predetermined pipes arranged on a processing-apparatus-20-side are connected to the air-supply port 12 and the exhaust port 13, as indicated by arrows of FIG. 4, the replacement gas is supplied into the pod 1 through the air-supply port 12 and exhausted from the pod 1 through the exhaust port 13.
Further, Japanese Patent Application Laid-Open No. 2007-273697 discloses an example in which an air-supply port and an exhaust port are arranged in a lid member of a pod. Japanese Patent Application Laid-Open No. 2007-273697 discloses replacement-gas flow; specifically, the replacement gas having been sent from the air-supply port of the lid member into the pod is brought into circulation in the pod and is exhausted from the exhaust port of the lid member to the outside of the pod. Specifically, in the pod disclosed in Japanese Patent Application Laid-Open No. 2007-273697, a gas-introducing pipe including squirt holes and extending in a vertical direction is attached to the lid member so that the replacement gas is introduced from the gas-introducing pipe into the pod.
In an arbitrary processing apparatus, when the lid member 2 closes the pod case 3 after completion of processing steps on substrates, the atmosphere in the pod case 3 is ambient atmosphere in a clean room, the ambient atmosphere containing dust. Thus, in the pod 1, it is necessary to replace the atmosphere in the pod 1 with the replacement gas so that the dust is not blown up and is prevented from adhering to the substrates. Thus, when the atmosphere in the pod 1 is replaced with the replacement gas, the replacement-gas flow in the pod 1 is required to enter a stable laminar state free from flow disturbance. Further, in order to completely replace the gas in the pod 1, it is necessary to achieve the replacement gas flow reaching throughout the pod 1 without stagnating therein. However, the pods disclosed in Japanese Patent Application Laid-Open No. 2003-17553, Japanese Patent Application Laid-Open No. 2003-60007, and Japanese Patent Application Laid-Open No. 2007-273697 are incapable of meeting the requirement for the following reasons.
As described in Japanese Patent Application Laid-Open No. 2003-17553 and Japanese Patent Application Laid-Open No. 2003-60007, when the air-supply port and the exhaust port are arranged in the lower portion of the pod 1, owing to limitation on sizes of the air-supply port and the exhaust port, an air-supply pipeline and an exhaust pipeline arranged therein are limited to narrow ones. Thus, it is difficult to arrange an air-supply port and an exhaust port which are suitable for requirement of the gas flow to be achieved. Specifically, after the pod 1 is placed on the load port portion 22, in many cases, a mechanism for moving the pod 1 to an appropriate position, a mechanism for locking the lid member 2 to the pod case 3, and the like are arranged in the lower portion of the pod 1 and the load port portion 22 which the lower portion of the pod 1 faces. Thus, limitation is imposed on arrangement of sizes of an air-supply port and an exhaust port of other mechanisms, and hence there is a problem in that the air-supply pipeline and the exhaust pipeline arranged therein are limited to narrow ones.
Further, as described in Japanese Patent Application Laid-Open No. 2003-17553 and Japanese Patent Application Laid-Open No. 2007-273697, even when the air-supply port and the exhaust port are arranged in a lid of the pod, owing to limitation on sizes of the air-supply port and the exhaust port, the problem still arises in that the air-supply pipeline and the exhaust pipeline arranged therein are limited to narrow ones. Specifically, it is difficult to arrange a valve member to a position optimal for functions of the valve member. This is because the lid member 2 is provided with a locking mechanism for opening and closing the lid in many cases, and hence, similarly to a case where the valve member is arranged in the lower portion of the pod, limitation is imposed on arrangement of the locking mechanism for opening and closing the lid. Thus, limitation is imposed also on sizes of the air-supply port and the exhaust port which can be arranged therein. As a result, even when the air-supply port and the exhaust port are arranged in the lid of the pod, as in Japanese Patent Application Laid-Open No. 2007-273697, the air-supply pipeline and the exhaust pipeline arranged therein are limited to narrow ones. As illustrated in Japanese Patent Application Laid-Open No. 2007-273697, when the elongated gas-introducing pipe including squirt holes and extending in a vertical direction is attached to the lid member so that the replacement gas is introduced from the gas-introducing pipe into the pod, flow-path resistance in a flow direction of the replacement gas in the gas-introducing pipe causes pressure gradient. As a result, uniform flow of the replacement gas cannot be achieved, and there is a risk that pressure variation in the gas-introducing pipe is directly transmitted into the pod.
That is, regarding air-supply and exhaust of the replacement gas with respect to the pod 1, when the air-supply port and the exhaust port provided with the air-supply pipeline and the exhaust pipeline are arranged, the pressure variation (pulse) of the replacement gas in the supply pipes has a direct influence on flow-rate variation of the replacement gas through the air-supply port and the exhaust port, the air-supply pipeline and the exhaust pipeline connected to the air-supply port and the exhaust port being limited to narrow ones. In order to obtain the replacement-gas flow in the stable laminar state free from disturbance, it is necessary to block the pressure variation (pulse) of the replacement gas in the supply pipes. Further, in order not to cause the pressure gradient at the supply ports of the replacement gas, it is necessary to arrange the squirt holes of the replacement gas.